IL-6, as a pro-inflammatory cytokine, has been proposed to contribute to the progression of rheumatoid arthritis and Crohn's disease, while SOCS3 is a major negative regulator of the IL-6-related cytokine-STAT3 pathway and enhanced expression of SOCS3 inhibits these inflammatory responses (11, 24, 25). Here, STAT3 is linked to rheumatoid arthritis.